Surgical stapling instrument incorporating a firing mechanism having a linked rack transmission

ABSTRACT

A surgical stapling and severing instrument particularly suited to endoscopic procedures incorporates a handle that produces separate closing and firing motions to actuate an end effector. In particular, the handle produces multiple firing strokes in order to reduce the required amount of force required to fire (i.e., staple and sever) the end effector. A linked transmission reduces the required handle longitudinal length, yet achieves a rigid, strong configuration when straightened for firing. A traction biased firing mechanism avoids binding in driving this straightened linked rack in cooperation with an anti-backup mechanism, with a lockout mechanism that prevents releasing the closure trigger during firing. Furthermore, an external indicator gives feedback to the surgeon as to how far firing has progressed, as well as providing a manual retraction capability.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is related to four co-pending and commonly-ownedapplications filed on even date herewith, the disclosure of each ishereby incorporated by reference in their entirety, these fourapplications being respectively entitled:

-   -   “SURGICAL STAPLING INSTRUMENT WITH MULTISTROKE FIRING        INCORPORATING AN ANTI-BACKUP MECHANISM, Ser. No. ______, to        Frederick E. Shelton, Mike Setser;    -   “SURGICAL STAPLING INSTRUMENT HAVING MULTISTROKE FIRING WITH        OPENING LOCKOUT, Ser. No. ______, to Frederick E. Shelton,        Jeffrey S. Swayze, Douglas B. Hoffman;    -   “SURGICAL STAPLING INSTRUMENT HAVING MULTISTROKE FIRING        INCORPORATING A TRACTION-BIASED RATCHETING MECHANISM, Ser. No.        ______, to Jeffrey S. Swayze, Frederick E. Shelton IV; and    -   “SURGICAL STAPLING INSTRUMENT INCORPORATING A MULTISTROKE FIRING        POSITION INDICATOR AND RETRACTION MECHANISM, Ser. No. ______, to        Jeffrey S. Swayze, Frederick E. Shelton IV.

FIELD OF THE INVENTION

The present invention relates in general to surgical stapler instrumentsthat are capable of applying lines of staples to tissue while cuttingthe tissue between those staple lines and, more particularly, toimprovements relating to stapler instruments and improvements inprocesses for forming various components of such stapler instrumentsthat accomplish firing with multiple strokes of a trigger.

BACKGROUND OF THE INVENTION

Endoscopic surgical instruments are often preferred over traditionalopen surgical devices since a smaller incision tends to reduce thepost-operative recovery time and complications. Consequently,significant development has gone into a range of endoscopic surgicalinstruments that are suitable for precise placement of a distal endeffector at a desired surgical site through a cannula of a trocar. Thesedistal end effectors engage the tissue in a number of ways to achieve adiagnostic or therapeutic effect (e.g., endocutter, grasper, cutter,staplers, clip applier, access device, drug/gene therapy deliverydevice, and energy device using ultrasound, RF, laser, etc.).

Known surgical staplers include an end effector that simultaneouslymakes a longitudinal incision in tissue and applies lines of staples onopposing sides of the incision. The end effector includes a pair ofcooperating jaw members that, if the instrument is intended forendoscopic or laparoscopic applications, are capable of passing througha cannula passageway. One of the jaw members receives a staple cartridgehaving at least two laterally spaced rows of staples. The other jawmember defines an anvil having staple-forming pockets aligned with therows of staples in the cartridge. The instrument includes a plurality ofreciprocating wedges which, when driven distally, pass through openingsin the staple cartridge and engage drivers supporting the staples toeffect the firing of the staples toward the anvil.

An example of a surgical stapler suitable for endoscopic applications isdescribed in U.S. Pat. No. 5,465,895, which advantageously providesdistinct closing and firing actions. Thereby, a clinician is able toclose the jaw members upon tissue to position the tissue prior tofiring. Once the clinician has determined that the jaw members areproperly gripping tissue, the clinician can then fire the surgicalstapler with a single firing stroke, thereby severing and stapling thetissue. The simultaneous severing and stapling avoids complications thatmay arise when performing such actions sequentially with differentsurgical tools that respectively only sever or staple.

One specific advantage of being able to close upon tissue before firingis that the clinician is able to verify via an endoscope that desiredlocation for the cut has been achieved, including a sufficient amount oftissue has been captured between opposing jaws. Otherwise, opposing jawsmay be drawn too close together, especially pinching at their distalends, and thus not effectively forming closed staples in the severedtissue. At the other extreme, an excessive amount of clamped tissue maycause binding and an incomplete firing.

Generally, a single closing stroke followed by a single firing stroke isa convenient and efficient way to perform severing and stapling.However, in some instances, it would be desirable for multiple firingstrokes to be required. For example, surgeons are able to select from arange of jaw sizes with a corresponding length of staple cartridge forthe desired length of cut. Longer staple cartridges require a longerfiring stroke. Thus, a hand-squeezed trigger to effect the firing isrequired to exert a larger force for these longer staple cartridges inorder to sever more tissue and drive more staples as compared to ashorter staple cartridge. It would be desirable for the amount of forceto be lower and comparable to shorter cartridges so as not to exceed thehand strength of some surgeons. In addition, some surgeons not familiarwith the larger staple cartridges may become concerned that binding orother malfunction has occurred when an unexpectedly higher force isrequired.

One approach to lower the required force for a firing stroke is aratcheting mechanism that allows a firing trigger to be stroked multipletimes, as described in U.S. Pat. Nos. 5,762,256 and 6,330,965. Theseknown surgical stapling instruments with multiple-stroke firingmechanisms do not have the advantages of a separate closure and firingaction. Moreover, the ratcheting mechanism relies upon a toothed rackand driving pawl to achieve the ratcheting motion, with the length of ahandle encompassing these components thus increased to accommodate thetoothed rack. This increased length is inconvenient given the closeconfines and increasing amount of equipment associated with a surgicalprocedure.

It is further desirable that fitting a multiple stroke firing mechanisminto a smaller handle does not come at the expense of achievable firingforce. Otherwise, reliable operation may be compromised, especiallyconsidering that certain portions of the firing stroke may experiencemore resistance.

Consequently, a significant need exists for a surgical staplinginstrument that uses multiple firing strokes to achieve a desired lengthof severing and stapling, and in particular such an instrument thatachieves this firing motion without lengthening the instrument handleand without limiting the achievable firing force that may be directedtherethrough.

BRIEF SUMMARY OF THE INVENTION

The invention overcomes the above-noted and other deficiencies of theprior art by providing a surgical stapling and severing instrument thatis capable of firing an implement portion that requires a large amountof firing travel and firing force. Yet, a handle of the instrument isadvantageously small and unobtrusive.

In another aspect of the invention, a surgical instrument has an endeffector that is responsive to a longitudinal firing motion to perform asurgical operation. A user causes movement in a firing actuator (e.g., atrigger) to create the firing motion that is selectively transferred bya firing mechanism into a plurality of linked members as a distallymoving longitudinal motion to the end effector.

In another aspect of the invention, a surgical instrument has an endeffector that is responsive to a longitudinal firing motion to perform asurgical operation. A handle portion has a pistol grip for a clinicianto grasp for positioning the end effector at a desired surgical site andfor producing the firing motion. Within the handle portion, a linkedrack is movable between a grip portion of the handle and its barrelportion that communicates with the end effector. A firing mechanismcouples the firing motion into the linked rack. Thereby, thelongitudinal size of the handle is reduced by retracting a portion ofthe firing components into the grip of the handle, rather than extendingfarther back. For end effector requiring a significant amount of travelfor firing, a substantial reduction in the size of the handle isachieved.

In yet another aspect of the invention, a surgical stapling and severinginstrument has an implement portion responsive to a firing motion anddiametrically dimensioned for endo-surgical use. Its implement portionincludes a shaft distally connected to an elongate channel from which ananvil pivots to form opposing jaws for clamping tissue. A firing barwith a distally presented cutting edge is longitudinally receivedbetween the elongate channel and the anvil. A staple device received inthe elongate channel responds to distal movement of the firing bar byforming staples against the anvil. A clinician causes this stapling andsevering by interacting with a handle containing a firing mechanism toproduce a firing motion. A rack means is responsive to the firingmechanism to rigidly drive the firing bar, yet the rack meanssubsequently bendably retracts within the handle.

These and other objects and advantages of the present invention shall bemade apparent from the accompanying drawings and the descriptionthereof.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention,and, together with the general description of the invention given above,and the detailed description of the embodiments given below, serve toexplain the principles of the present invention.

FIG. 1 is a right side elevation view of a surgical stapling andsevering instrument in an open (start) condition, with a shaft partiallycutaway to expose a closure tube and firing rod.

FIG. 2 is a left side elevation view taken along line 2-2 inlongitudinal cross section of an end effector at a distal portion of thesurgical stapling instrument of FIG. 1.

FIG. 3 is a front perspective view of the end effector of FIG. 2.

FIG. 4 is a perspective, exploded view of an implement portion of thesurgical stapling and severing instrument of FIG. 1.

FIG. 5 depicts a left side elevation view in section of the end effectorof FIG. 3 of the surgical instrument of FIG. 1, the section generallytaken along lines 5-5 of FIG. 3 to expose portions of a staple cartridgebut also depicting the firing bar along the longitudinal centerline.

FIG. 6 depicts a left side elevation view in section of the end effectorof FIG. 5 after the firing bar has fully fired.

FIG. 7 is a left side elevation view of the handle of the surgicalstapling and severing instrument of FIG. 1 with a left handle housingremoved.

FIG. 8 is a perspective, exploded view of the handle of FIG. 7.

FIG. 9 is a perspective view from an elevated, aft, left vantage pointof the linked transmission firing mechanism of the handle of FIG. 7.

FIG. 10 is a detail left side elevation view of the linked rack of thefiring mechanism of FIG. 9.

FIGS. 11-14 are left side elevation views in cross section generallyalong the longitudinal axis of the ramped central track of the linkedrack and the pawl of the firing mechanism, and additionally showing thefiring trigger, biasing wheel and ramp of the traction biasingmechanism, depicting a sequence during a firing stroke.

FIG. 15 is a right-side elevation view partially disassembled to exposea distal portion of an anti-backup mechanism in a locked condition inthe surgical stapling and severing instrument of FIG. 1.

FIG. 16 is a perspective view from a top, aft, right vantage point ofthe anti-backup mechanism of FIG. 15 with the anti-backup cam tuberemoved.

FIG. 17 is a right-side elevation view partially disassembled to exposea distal portion of an anti-backup mechanism in an unlocked condition inthe surgical stapling and severing instrument of FIG. 1.

FIG. 18 is a right-side elevation view partially disassembled to exposea distal portion of an anti-backup mechanism in an unlocked condition inthe surgical stapling and severing instrument of FIG. 1.

FIG. 19 is a rear elevation view of the surgical stapling and severinginstrument of FIG. 1 with the right half shell of the handle housingremoved to expose the anti-backup release lever in phantom in a lockingcondition and in an unlocked condition.

FIGS. 20-25 are detail views of the anti-backup release lever of FIG. 18depicting respectively a firing sequence of unfired, one firing stroke,two firing strokes, three firing strokes, returning or release buttonpushed, and fully returned.

FIGS. 26-27 are perspective view from a top, left, distal vantage pointof the surgical stapling and severing instrument with the right halfshell of the handle housing removed to expose a closure release lockoutmechanism, respectively in an initial position with lockout removed andclosure release button depressed, and then a lockout being activatedduring initial firing.

FIG. 28 is perspective view of a surgical stapling and severinginstrument in an open condition similar to FIG. 1 but incorporating atop-accessible retraction lever.

FIG. 29 is a left side elevation view of the surgical stapling andsevering instrument of FIG. 28 with the left half shell of the handlehousing removed to expose an intermittently toothed indicator gearpresenting a first dwell area to the idler gear.

FIG. 30 is a left side elevation view of the surgical stapling andsevering instrument of FIG. 28 with the left half shell of the handlehousing removed to expose an intermittently toothed indicator gearpresenting a second dwell area to the idler gear.

DETAILED DESCRIPTION OF THE INVENTION

Turning to the Drawings, wherein like numerals denote like componentsthroughout the several views, FIGS. 1 and 2 depict a surgical staplingand severing instrument 10 that is capable of practicing the uniquebenefits of the present invention. The surgical stapling and severinginstrument 10 incorporates an end effector 12 having an anvil 14pivotally attached to an elongate channel 16, forming opposing jaws forclamping tissue to be severed and stapled. The end effector 12 iscoupled by a shaft 18 to a handle 20. An implement portion 22, formed bythe end effector 12 and shaft 18, is advantageously sized for insertionthrough a trocar or small laparoscopic opening to perform an endoscopicsurgical procedure while being controlled by a surgeon grasping thehandle 20. The handle 20 advantageously includes features that allowseparate closure motion of the end effector 12 from firing, as well asenabling multiple firing strokes to effect firing (i.e., severing andstapling) of the end effector 12 while indicating the degree of firingto the surgeon.

To these ends, a closure tube 24 of the shaft 18 is coupled between aclosure trigger 26 and the anvil 14 to cause closure of the end effector12. Within the closure tube 24, a frame 28 is coupled between theelongate channel 16 and the handle 20 to longitudinally position andsupport the end effector 12. A rotation knob 30 is coupled with theframe 28, and both elements are rotatably coupled to the handle 20 withrespect to a rotational movement about a longitudinal axis of the shaft18. Thus, the surgeon can rotate the end effector 12 by turning therotation knob 30. The closure tube 24 is also rotated by the rotationknob 30 but retains a degree of longitudinal movement relative theretoto cause the closure of the end effector 12. Within the frame 28, afiring rod 32 is positioned for longitudinal movement and coupledbetween the anvil 14 of the end effector 12 and a multiple-stroke firingtrigger 34. The closure trigger 26 is distal to a pistol grip 36 of thehandle 20 with the firing trigger 34 distal to both the pistol grip 36and closure trigger 26.

In endoscopic operation, once the implement portion 22 is inserted intoa patient to access a surgical site, a surgeon refers to an endoscopicor other diagnostic imaging device to position tissue between the anvil14 and elongate channel 16. Grasping the closure trigger 26 and pistolgrip 36, the surgeon may repeatedly grasp and position the tissue. Oncesatisfied as to the location of the tissue relative to the end effector12 and the amount of tissue therein, the surgeon depresses the closuretrigger 26 fully toward the pistol grip 36, clamping the tissue in theend effector 12 and locking the closure trigger 26 in this clamped(closed) position. If not satisfied with this position, the surgeon mayrelease the closure trigger 26 by depressing a closure release button 38and thereafter repeat the procedure to clamp tissue.

If clamping is correct, the surgeon may proceed with firing the surgicalstapling and severing instrument 10. Specifically, the surgeon graspsthe firing trigger 34 and pistol grip 36, depressing the firing trigger34 a predetermined number of times. The number of firing strokesnecessary is ergonomically determined based on a maximum hand size,maximum amount of force to be imparted to the instrument during eachfiring stroke, and the longitudinal distance and force needed to betransferred through the firing rod 32 to the end effector 12 duringfiring. As will be appreciated in the discussion below, individualsurgeons may choose to cycle the firing trigger 34 a different angularrange of motion, and thus increase or decrease the number of firingstrokes, yet the handle 20 still effects firing without binding.

During these strokes, the surgeon may reference an indicator, depictedas an indicating retraction knob 40, that positionally rotates inresponse to the multiple firing strokes. Additionally, the position ofthe retraction knob may confirm that full firing has occurred whenencountering resistance to further cycling of the firing trigger 34. Itshould be appreciated that various indicia and instructions may be addedto the handle 20 to enhance the indication provided by the rotation ofthe indicating retraction knob 40. Upon full travel of the firing rod 32and when the firing trigger 34 is released, the handle 20 automaticallyretracts the firing rod 32. Alternatively, the surgeon, with knowledgethat the instrument 10 has not fully fired as depicted by the indicatingretraction knob 40, may depress an anti-backup release button 42 andrelease the firing trigger 34. Both of these actions allow the handle 20to automatically retract the firing rod 32.

It will be appreciated that the terms “proximal” and “distal” are usedherein with reference to a clinician gripping a handle of an instrument.Thus, the end effector 12 is distal with respect to the more proximalhandle 20. It will be further appreciated that for convenience andclarity, spatial terms such as “vertical” and “horizontal” are usedherein with respect to the drawings. However, surgical instruments areused in many orientations and positions, and these terms are notintended to be limiting and absolute.

The present invention is being discussed in terms of endoscopicprocedures and apparatus. However, use herein of terms such as“endoscopic”, should not be construed to limit the present invention toa surgical stapling and severing instrument for use only in conjunctionwith an endoscopic tube (i.e., trocar). On the contrary, it is believedthat the present invention may find use in any procedure where access islimited to a small incision, including but not limited to laparoscopicprocedures, as well as open procedures.

E-Beam End Effector.

The advantages of a handle 20 capable of providing multiple-strokefiring motion has application to a number of instruments, with one suchend effector 12 being depicted in FIGS. 2-6. The end effector 12responds to the closure motion from the handle 20 (not depicted in FIGS.2-6) first by including an anvil face 50 (FIGS. 2, 4, 6) connecting toan anvil proximal end 52 that includes a pair of laterally projectinganvil pivot pins 54 that are distal to a vertically projecting anvilfeature 56 (FIG. 4). The anvil pivot pins 54 translate within kidneyshaped openings 58 in the elongate channel 16 to open and close anvil 14relative to elongate channel 16. The anvil feature 56 engages a bent tab59 extending inwardly in tab aperture 60 on a distal end 62 of theclosure tube 24, the latter distally terminating in a distal edge 64that pushes against the anvil face 50. Thus, when the closure tube 24moves proximally from its the open position, the bent tab 59 of theclosure tube 24 draws the anvil feature 56 proximally, and the anvilpivot pins 54 follow the kidney shaped openings 58 of the channel 16causing the anvil 14 to simultaneously translate proximally and rotateupward to the open position. When the closure tube 24 moves distally,the tab aperture 60 releases from the anvil feature 56 and the distaledge 64 pushes on the anvil face 50, closing the anvil 14.

With continued reference to FIG. 4, the implement portion 22 alsoincludes components that respond to the firing motion of the firing rod32. In particular, the firing rod 32 rotatably engages a firing troughmember 66 having a longitudinal recess 68. Firing trough member 66 moveslongitudinally within frame 28 in direct response to longitudinal motionof firing rod 32. A longitudinal slot 70 in the closure tube 24 operablycouples with the rotation knob 30 (not shown in FIGS. 2-6). The lengthof the longitudinal slot 70 in the closure tube 24 is sufficiently longas to allow relative longitudinal motion with the rotation knob 30 toaccomplish firing and closure motions respectively.

The distal end of the frame trough member 66 is attached to a proximalend of a firing bar 76 that moves with the frame 28, including a guide78 therein, to distally project an E-beam 80 into the end effector 12.The end effector 12 includes a staple cartridge 82 that is actuated bythe E-beam 80. The staple cartridge 82 has a tray 84 that holds a staplecartridge body 86, a wedge sled driver 88, staple drivers 90 and staples92. It will be appreciated that the wedge sled driver 88 longitudinallymoves within a recess 94 located between a cartridge tray 84 and thecartridge body 86. The wedge sled driver 88 presents camming surfacesthat contact and lift the staple drivers 90 upward, driving the staples92 up from staple apertures 96 into contact with staple forming grooves98 of the anvil 14, creating formed “B” shaped staples, such as depictedat 100 of FIG. 6. With particular reference to FIG. 3, the staplecartridge body 86 further includes a proximally open, vertical slot 102for passage of the E-beam 80. Cutting surface 104 is provided along adistal end of E-beam 80 to cut tissue after it is stapled.

In FIGS. 2, 5, 6, respectively, the end effector 12 is depicted in asequence of open (i.e., start) condition, clamped and unfired condition,and fully fired condition. Features of the E-beam 80 that facilitatefiring of the end effector 12, in particular, are depicted. In FIG. 2,the wedge sled driver 88 is in its fully proximally position, indicatingan unfired staple cartridge 82. A middle pin 106 is aligned to enter thefiring recess 94 in the staple cartridge 82, for distally driving thewedge sled driver 88. A bottom pin or cap 108 of the E-beam 82 slidesalong a bottom surface of the elongate channel 16, thus the middle andbottom pins 106, 108 slidingly engage the elongate channel 16. In theopen and unfired state of FIG. 2, a top pin 110 of the E-beam 80 hasentered and is residing within an anvil pocket 112 of the anvil 14, andthus does not impede repeated opening and closing of the anvil 14.

In FIG. 5, the end effector 12 is depicted as clamped and ready to fire.The top pin 110 of the E-beam 80 is aligned with an anvil slot 114 inthe anvil 14 distal to and communicating with the anvil pocket 112. InFIG. 6, the E-beam 80 has been fully fired, with the upper pin 110translating down the anvil slot 114, affirmatively spacing the anvil 14from the elongate channel 16 as the cutting surface 104 severs clampedtissue. Simultaneously, the middle pin 106 has actuated the staplecartridge 82 as previously described. Thereafter, the E-beam 80 isretracted prior to opening the end effector 12 and replacing the staplecartridge 82 for an additional operation.

The illustrative end effector 12 is described in greater detail in fiveco-pending and commonly-owned U.S. patent applications, the disclosureof each being hereby incorporated by reference in their entirety: (1)“SURGICAL STAPLING INSTRUMENT HAVING A SINGLE LOCKOUT MECHANISM FORPREVENTION OF FIRING”, Ser. No. 10/441,424, to Frederick E. Shelton,Mike Setser, Bruce Weisenburgh, filed 20 Jun. 2003; (2) “SURGICALSTAPLING INSTRUMENT HAVING SEPARATE DISTINCT CLOSING AND FIRINGSYSTEMS”, Ser. No. 10/441,632, to Frederick E. Shelton, Mike Setser,Brian J. Hemmelgarn, filed 20 Jun. 2003; (3) “SURGICAL STAPLINGINSTRUMENT HAVING A SPENT CARTRIDGE LOCKOUT”, Ser. No. 10/441,565, toFrederick E. Shelton, Mike Setser, Bruce Weisenburgh, filed 20 Jun.2003; (4) “SURGICAL STAPLING INSTRUMENT HAVING A FIRING LOCKOUT FOR ANUNCLOSED ANVIL”, Ser. No. 10/441,580, to Frederick E. Shelton, MikeSetser, Bruce Weisenburgh, filed 20 Jun. 2003; and (5) “SURGICALSTAPLING INSTRUMENT INCORPORATING AN E-BEAM FIRING MECHANISM”, Ser. No.10/443,617, to Frederick E. Shelton, Mike Setser, Bruce Weisenburgh,filed 20 Jun. 2003.

It should be appreciated that although a nonarticulating shaft 18 isillustrated herein, applications of the present invention may includeinstruments capable of articulation, such as described in fiveco-pending and commonly owned U.S. patent applications, the disclosureof each being hereby incorporated by reference in their entirety: (1)“SURGICAL INSTRUMENT INCORPORATING AN ARTICULATION MECHANISM HAVINGROTATION ABOUT THE LONGITUDINAL AXIS”, Ser. No. 10/615,973, to FrederickE. Shelton, Brian J. Hemmelgarn, Jeff Swayze, Kenneth S. Wales, filed 9Jul. 2003; (2) “SURGICAL STAPLING INSTRUMENT INCORPORATING ANARTICULATION JOINT FOR A FIRING BAR TRACK”, Ser. No. 10/615,962, toBrian J. Hemmelgarn, filed 9 Jul. 2003; (3) “A SURGICAL INSTRUMENT WITHA LATERAL-MOVING ARTICULATION CONTROL”, Ser. No. 10/615,972, to JeffSwayze, filed 9 Jul. 2003; (4) “SURGICAL STAPLING INSTRUMENTINCORPORATING A TAPERED FIRING BAR FOR INCREASED FLEXIBILITY AROUND THEARTICULATION JOINT”, Ser. No. 10/615,974, to Frederick E. Shelton, MikeSetser, Bruce Weisenburgh, filed 9 Jul. 2003; and (5) “SURGICAL STAPLINGINSTRUMENT HAVING ARTICULATION JOINT SUPPORT PLATES FOR SUPPORTING AFIRING BAR”, Ser. No. 10/615,971, to Jeff Swayze, Joseph Charles Hueil,filed 9 Jul. 2003.

It should further be appreciated that the linked rack 200 further mayenhance a compact design for the handle 20 by progressing at leastpartially into the shaft 18 of the implement portion 22 as well asaround a corner and into a pistol grip 36 of the handle. Moreover,instead of communicating the firing force to a firing rod 32, a linkedrack consistent with aspects of the invention may travel farther towardthe end effector 12 to include an articulation mechanism. A pivotalconnection between links may thus enhance the ability of the instrumentto articulate.

Multi-Stroke Firing Handle.

In FIGS. 7-8, the handle 20 of the surgical stapling and severinginstrument 10 is shown in greater detail, illustrating a linkedtransmission firing mechanism 150 that provides features such asincreased strength, reduced handle size, minimized binding, etc.

Closure of the end effector 12 (not shown in FIGS. 7-8) is caused bydepressing the closure trigger 26 toward the pistol grip 36 of handle20. The closure trigger 26 pivots about a closure trigger pin 152 thatis coupled to a handle housing 154 composed of right and left halfshells 156, 158, causing an upper portion 160 of the closure trigger 26to move forward. The closure tube 24 receives this closure movement viaa closure yoke 162 that is pinned to a closure link 164 and to the upperportion 160 of the closure trigger 26 respectively by a closure yoke pin166 and a closure link pin 168.

In the fully open position of FIG. 7, the upper portion 160 of theclosure trigger 26 contacts and holds a locking arm 172 of the pivotingclosure release button 38 in the position shown. When the closuretrigger 26 reaches its fully depressed position, the closure trigger 26releases the locking arm 172 and an abutting surface 170 rotates intoengagement with a distal rightward notch 171 of the pivoting locking arm172, holding the closure trigger 26 in this clamped or closed position.A proximal end of the locking arm 172 pivots about a lateral pivotalconnection 174 with the housing 154 to expose the closure release button38. An intermediate, distal side 178 of the closure release button 38 isurged proximally by a compression spring 180, which is compressedbetween a housing structure 182 and closure release button 38. Theresult is that the closure release button 38 urges the locking arm 172counterclockwise (when viewed from the left) into locking contact withthe abutting surface 170 of closure trigger 26, which preventsunclamping of closure trigger 26 when the linked transmission firingsystem 150 is in an unretracted condition, as described in greaterdetail below.

With the closure trigger 26 retracted fully depressed, the firingtrigger 34 is unlocked and may be depressed toward the pistol grip 36multiple times to effect firing of the end effector 12. As depicted, thelinked transmission firing mechanism 150, is initially retracted, urgedto remain in this position by a combination tension/compression spring184 that is constrained within the pistol grip 36 of the handle 20, withits nonmoving end 186 connected to the housing 154 and a moving end 188connected to a downwardly flexed and proximal, retracted end 190 of asteel band 192.

A distally-disposed end 194 of the steel band 192 is attached to a linkcoupling 195 for structural loading and front link 196 a of a pluralityof links 196 a-196 d that form a linked rack 200. Linked rack 200 isflexible yet has distal links that form a straight rigid rack assemblythat may transfer a significant firing force through the firing rod 32in the implement portion 22, yet readily retract into the pistol grip 36to minimize the longitudinal length of the handle 20.

It should be appreciated that a dual tension/compression spring 184increases the amount of firing travel available while essentiallyreducing the minimum length by half over a single spring.

The firing trigger 34 pivots about a firing trigger pin 202 that isconnected to the housing 154. An upper portion 204 of the firing trigger34 moves distally about the firing trigger pin 202 as the firing trigger34 is depressed towards pistol grip 36, stretching a proximally placedfiring trigger tension spring 206 proximally connected between the upperportion 204 of the firing trigger 34 and the housing 154. The upperportion 204 of the firing trigger 34 engages the linked rack 200 duringeach firing trigger depression by a traction biasing mechanism 210 thatalso disengages when the firing trigger 34 is released. Firing triggertension spring 206 urges the firing trigger 34 distally when releasedand disengages the traction biasing mechanism 210.

As the firing mechanism 150 actuates, an idler gear 220 is rotatedcounterclockwise (as viewed from the left side) by engagement with atoothed upper surface 222 of the linked rack 200. This rotation iscoupled to an indicator gear 230, which thus rotates clockwise inresponse to the idler gear 220. Both the idler gear 220 and indicatorgear 230 are rotatably connected to the housing 154. The gearrelationship between the linked rack 200, idler gear 220 and indicatorgear 230 may be advantageously selected so that the toothed uppersurface 222 has tooth dimensions that are suitably strong and that theindicator gear 230 makes no more than one revolution during the fullfiring travel of the firing mechanism 150.

As described in greater detail below, the indicator gear 230 performs atleast four functions. First, when the linked rack 200 is fully retractedand both triggers 26, 34 are open as shown in FIG. 7, an opening 240 ina circular ridge 242 on the left side of the indicator gear 230 ispresented to an upper surface 244 of the locking arm 172. Locking arm172 is biased into the opening 240 by contact with the closure trigger26, which in turn is urged to the open position by a closure tensionspring 246. Closure trigger tension spring 246 is connected proximallyto the upper portion 160 of the closure trigger 26 and the handlehousing 154, and thus has energy stored during closing of the closuretrigger 26 that urges the closure trigger 26 distally to its unclosedposition.

A second function of the indicator gear 230 is that it is connected tothe indicating retraction knob 40 externally disposed on the handle 20.Thus, the indicator gear 230 communicates the relative position of thefiring mechanism 150 to the indicating retraction knob 40 so that thesurgeon has a visual indication of how many strokes of the firingtrigger 34 are required to complete firing.

A third function of the indicator gear 230 is to longitudinally and toangularly move an anti-backup release lever 248 of an anti-backupmechanism 250 as the surgical stapling and severing instrument 10 isoperated. During the firing strokes, proximal movement of anti-backuprelease lever 248 by indicator gear 230 activates a one-way clutchmechanism or anti-backup 250 (FIGS. 15-16) that allows distal movementof firing bar 32 and prevents proximal motion of firing bar 32. Thismovement also extends the anti-backup release button 42 from theproximal end of the housing 154 for the operator to actuate should theneed arise for the firing mechanism to be retracted during the firingstrokes. After completion of the firing strokes, the indicator gear 230reverses direction of rotation as the firing mechanism 150 retracts. Thereversed rotation deactivates the anti-backup 250, withdraws theanti-backup release button 42 into the handle 20, and rotates theanti-backup release lever 248 laterally (FIG. 19) to allow continuedreverse rotation of the indicator gear 230.

A fourth function of the indicator gear 230 is to receive a manualrotation from the indicating retraction knob 40 (clockwise in thedepiction of FIG. 7) to retract the firing mechanism 150 withanti-backup mechanism 250 is unlocked, thereby overcoming any binding inthe firing mechanism 150 that is not readily overcome by the combinationtension/compression spring 184. This manual retraction may be employedafter a partial firing of the firing mechanism 150 that would otherwisebe prevented by the anti-backup mechanism 250 by depression of theanti-backup release button 42, which laterally moves the anti-backuprelease lever 248.

Anti-backup mechanism 250 consists of an operator accessible anti-backuprelease lever 248 operably coupled at the proximal end to anti-backuprelease lever 42 and at the distal end to an anti-backup yoke 256. Inparticular, a distal end 254 of the anti-backup release lever 248 isengaged to the anti-backup yoke 256 by an anti-backup yoke pin 258. Theanti-backup yoke 256 moves longitudinally to impart a rotation to ananti-backup cam slot tube 252 that is longitudinally constrained by thehousing 154 and that encompasses the firing rod 32 distally to theconnection of the firing rod 32 to the front link 196 a of the linkedrack 200. The anti-backup yoke 256 communicates the longitudinalmovement from the anti-backup release lever 248 via a cam slot tube pin260 to the anti-backup cam slot tube 252. That is, longitudinal movementof cam slot tube pin 260 in an angled slot in the anti-backup cam slottube 252 rotates the tube 252.

Trapped between a proximal end of the frame 28 and the anti-backup camslot tube 252 respectively are an anti-backup compression spring 264, ananti-backup plate 266, and an anti-backup cam tube 268. As depicted,distal movement of the firing rod 32 causes the anti-backup plate 266 topivot top to the rear, presenting an increased frictional contact to thefiring rod 32 that resists proximal movement of the firing rod 32.

This anti-backup plate 266 pivots in a manner similar to that of ascreen door lock that holds open a screen door when the anti-backup camslot tube 252 is spaced away from the anti-backup cam tube 268.Specifically, the anti-backup compression spring 264 is able to act upona top surface of the plate 266 to tip the plate 266 to its lockedposition. Rotation of the anti-backup cam slot tube 252 causes a distalcamming movement of the anti-backup cam tube 268 forcing the top of theplate 266 distally, overcoming the force from the anti-backupcompression spring 264, thus positioning the anti-backup plate 266 in anunlocked position that allows proximal retraction of the firing rod 32.

With particular reference to FIGS. 8-10, the traction biasing mechanism210 is depicted as being composed of a pawl 270 that has a distallyprojecting narrow tip 272 and a rightwardly projecting lateral pin 274at its proximal end that is rotatably inserted through a hole 276 in theupper portion 204 of the firing trigger 34. On the right side of thefiring trigger 34, the lateral pin 274 receives a biasing member,depicted as biasing wheel 278. As the firing trigger 34 translates foreand aft, the biasing wheel 278 traverses an arc proximate to the righthalf shell 156 of the handle housing 154, overrunning at its distalportion of travel a biasing ramp 280 integrally formed in the right halfshell 156. The biasing wheel 278 may advantageously be formed from aresilient, frictional material that induces a counterclockwise rotation(when viewed from the left) into the lateral pin 274 of the pawl 270,thus traction biasing the distally projecting narrow tip 272 downwardinto a ramped central track 282 of the nearest link 196 a-d to engagethe linked rack 200. As the firing trigger 34 is released, the biasingwheel 278 thus tractionally biases the pawl 270 in the oppositedirection, raising the narrow tip 272 from the ramped central track 282of the linked rack 200. To ensure disengagement of the tip 272 underhigh load conditions and at nearly full distal travel of the pawl 270,the narrow tip 272 ramps up onto a proximally and upwardly facingbeveled surface 284 on the closure yoke 162 to disengage the narrow tip272 from the ramped central track 282. If the firing trigger 34 isreleased at any point other than full closure, the biasing wheel 278 isused to lift the narrow tip 272 from the ramped central track 282.Whereas a biasing wheel 278 is depicted, it should be appreciated thatthe shape of the biasing member or wheel 278 is illustrative and may bevaried to accommodate a variety of shapes that use friction or tractionto engage or disengage the firing of the end effector.

Linked Rack.

With particular reference to FIG. 10, the linked rack 200 is depicted ingreater detail to illustrate a number of advantages. Each link 196 a-dis pinned to adjacent links 196 a-d for downward, proximal rotation intothe pistol grip 36. Although bendable in this direction, the linked rack200 forms a rigid configuration when against a columnar loading,especially a loading that would other urge the distal links 196 a-d tobend upwardly. In particular, each link 196 a-d proximally terminates ina male extension 300 having lateral through hole 302 on a lower portionthereof. A left side 304 of each link 196 a-d includes the toothed uppersurface 222 and a right side 306 parallels the left side 304 definingbetween them the ramped central track 282 that terminates in the maleextension 300.

The proximal portion of the central track 282 terminates before theright and left sides 304, 306, forming a device 308 for receiving a maleextension 300 from a leading link 196 a-d, which is hingedly attached bya pivot pin 310. Each leading link 196 a-d has a flat 312 at theproximal end that is generally perpendicular to the direction ofcolumnar loading from the firing rod 32. Each trailing link 196 a-d hasa contact surface 314 at the distal end that is also generallyperpendicular to the direction of columnar loading. The lateral throughhole 302 is spaced away sufficient so that a notch 316 is formed betweenlower portions of adjacent flat 312 and contact surface 314 to provideclearance for downward pivoting of the trailing link 196 a-d relative tothe leading link 196 a-d. Yet, the upper portions of the adjacent flat312 and contact surface 314 are registered for abutment as the leadingand trailing links 196 a-d are longitudinally aligned, thereby resistingfurther upward deflection. As shown, when adjacent links 196 a-d arehorizontal, the holes 302 and pins 310 are located below the line ofaction of the firing rod 32. When loads are applied to the firingtrigger 34, the traction biasing mechanism 210 applies a pushing loadalong the line of action and biases consecutive horizontal links 196 a-dtogether. Thus, imparting a line of action of a firing force above thepivot pins 310 maintains any leading links 196 a-d in a rigid, straightconfiguration. The ramped central track 282 of a trailing link 196 b-ddirects the distally projecting narrow tip 272 of the pawl 270 intoengagement with the male extension 300 of the leading link 196 a-c.

The front link 196 a is distally attached to the link coupling 195 thatincludes features that couple to the proximal end of the firing rod 32as well as including a male extension 300 and flat 312 similar to thelinks 196 a-d, with sufficient spacing to receive therebetween tabs 320,322 (FIG. 8) of the distally-disposed end 194 of the steel band 192, thetabs 320, 322 attached by the same pivot pin 310 that attaches the frontlink 196 a to the link coupling 195. Application of the retraction forceat this force advantageously reduces frictional forces by applying theforce along the longitudinal axis of the firing rod 32 and straightportion of the linked rack 200.

Having a toothed upper surface 222 on the left side 304 that is distinctfrom the ramped central track 282 advantageously allows a nonbinding,strong engagement between the pawl 270 and the linked rack 200, even ifthe firing trigger 34 has been stroked with varying ranges of motion.Meanwhile the toothed upper surface 222 provides a continuous engagementwith the idler gear 220 for the advantages described above.

It should be appreciated that although a pinned clevis connectionbetween links 196 a-d has been advantageously depicted, a resilient orflexible connection may be used. In addition, four links 196 a-d aredepicted, but various numbers and lengths of links may be selecteddepending on firing travel, radius of curvature, etc.

Traction-Biasing Mechanism.

In FIGS. 11-14, the linked transmission firing mechanism 150 is depictedin a sequence that illustrates how the traction biasing mechanism 210(i.e., pawl 270, biasing wheel 278, and biasing ramp 280) affirmativelyrespond to the direction of travel of the firing trigger 34. Moreover,since the biasing wheel 278 makes a frictional contact with the biasingramp 280, the biasing wheel 278 slides when full disengagement orengagement movement of the pawl 270 is achieved.

In FIG. 11, the firing trigger 34 has been partially depressed to wherethe traction biasing mechanism 210 begins to initiate engagement of thefiring trigger 34 movement to the linked rack 200. In particular, thebiasing wheel 278 has contacted the proximal end of the biasing ramp280, and thus begins to rotate counterclockwise, as viewed from theleft, imparting this rotation to the pawl 270, which is initiallydisengaged from the linked rack 200. In FIG. 12, the firing mechanism150 has advanced a distance sufficient for the pawl 270 to have fullyrotated into engagement with the ramped central track 282 of the firstlink 196 a, abutting the link coupling 195 and thereby transferring afiring motion into the firing rod 32. In FIG. 13, the firing trigger 34and overall firing mechanism 150 has continued to a nearly full travelposition, during which movement the biasing wheel 278 has slid along thebiasing ramp 280. At the end of the firing stroke, the farside loweredge of the pawl 270 (FIG. 8) contacts the proximally and upwardlyfacing beveled surface 284 of the closure yoke 162 and lifts the pawl270 from engagement with a link 196, allowing the linked rack 200 toretract.

In FIG. 14, the firing trigger 34 has been released sufficient for thebiasing wheel 278 to gain traction proximally on the biasing ramp 280,causing a clockwise rotation, when viewed from the left, and raising thepawl 270. Given the proximally directed slope of the ramped centraltrack 282 of the linked rack 200, the firing mechanism 150 is notobstructed in being moved proximally in preparation for either anotherfiring stroke or for a retraction cycle.

It should be appreciated that the traction biasing mechanism 210 may beimplemented in an instrument that performs at least a single stroke.

Anti-Backup Mechanism.

As described above, the anti-backup mechanism 250 locks during thefiring strokes to prevent the firing rod 32 and thus the firingmechanism 150 from retracting until full firing travel is achieved orthe user selects to retract. In FIG. 15, the anti-backup mechanism 250is depicted in a locked condition. The anti-backup release lever 248 isin the proximal-most position and has rotated anti-backup cam slot tube252 to engage the anti-backup cam tube 268 to form a minimumlongitudinal length, creating an increased space for the locking plate266. Locking plate 266 is tipped to the angle shown by the anti-backupcompression spring 264 and grips on the firing rod 32, as shown in FIG.16.

In FIG. 16, a proximal end 400 of the frame 28 include a half spoolportion 402 that receives the anti-backup compression spring 264 againstits distal annular ring 404. Proximal to the spring 264, the frame 28has a top and proximally open trough 406 that communicates with theinterior of the frame 28. The anti-backup plate 266 is a generally flatplate shaped to fit into the open trough 406 adjacent to the spring 264.Central orifice 408 extends through plate 266. In particular, the topportion of the anti-backup plate 266 that is exposed from the opentrough 406 projects upwardly to receive a force from the spring 264. Thelower portion of the anti-backup plate 266 is longitudinally constrainedand not in contact with the spring 264. Thus, unless restrained by theanti-backup cam tube 268, the top of the anti-backup plate 266 is urgedto tip proximally, causing the central orifice 408 in the anti-backupplate 266 to bind against the firing rod 32.

In FIG. 17, the anti-backup mechanism 250 is depicted as unlocked. Theanti-lock release lever 248 has laterally moved to the right, impart amovement to the right of the anti-backup yoke 256, thereby imparting aclockwise rotation of the anti-backup cam slot tube 252, when viewedfrom a proximal position. A camming surface 410 of the anti-backup camslot tube 252 departs from a proximal cutout 412 in the anti-backup camtube 268, forcing the latter to move distally against the anti-backupplate 266, which in turn moves to a perpendicular, unlocked position andfurther compresses anti-backup compression spring 264.

In FIG. 18, the interaction between the anti-backup release lever 248and the right side of the indicator gear 230 are depicted after thefiring trigger 34 has been fired twice. A lever opening 420 extendsthrough anti-backup release lever 248 to receive and interact with acurved ramp 434 extending outwardly from the right side of the indicatorgear 230. Rotation of the indicator gear 230 drives the anti-backuprelease lever 248 distally, which bottoms out the anti-backup releasebutton 42 into a button receptacle 422 and disengages the anti-backupmechanism 250, and proximally, which exposes the anti-backup releasebutton 42 as depicted, as well as kicking the anti-backup release lever248 to the right to actuate the anti-backup mechanism 250. Theanti-backup yoke 256 allows this motion with a longitudinal slottedconnection with the anti-backup yoke pin 258 (not shown). Thesemovements of the anti-backup release lever 248 are caused by a curvedramp 430 that surrounds almost a quarter of the circumference of anindicator pin 432, about which the indicator gear 230 turns. Theclockwise most portion (when viewed from the right), or peak 434, of thecurved ramp 430 projects the farthest to the right away from the surfaceof the indicator gear 230. The counterclockwise most portion or entry436 of the curved ramp 430 is thus flush with the surface of theindicator gear 230.

In FIGS. 18-25, the lever opening 420 is shaped with a horizontal slot440 that defines the proximal and distal movement available to theanti-backup release lever 248, with the indicator pin 432 residingwithin this horizontal slot 440. A top recess 442 and a bottom recess444 vertically widen and communicate with the horizontal slot 440 anddefine at what angular position the clockwise most portion 434 of thecurved ramp 430 longitudinally translates the anti-backup release lever248. The top and bottom recesses 442, 444 are sized to allow the curvedramp 430 to enter the respective recess 442, 444 without tipping theanti-backup release lever 248 until the end of normal firing. The leveropening 420 is above the longitudinal axis of the anti-backup mechanism250, and thus a rightward force creates a rotating force of theanti-backup cam slot tube 252.

In FIG. 20, the anti-backup release lever 248 and indicator gear 230 areshown in their initial condition that remains through the time in whichthe closure trigger 26 is being actuated. In particular, the anti-backuprelease lever 248 is distally positioned, bottoming out the anti-backuprelease button 42 in its button receptacle 422. The curved ramp 430 isat its counterclockwise extreme, with its peak 434 at approximately the6 o'clock position adjacent distally to a proximal vertical surface ofthe lower recess 444 of the lever recess 420 with the entry 436 of theramp 430 at about 3 o'clock.

In FIG. 21, the first firing stroke of the firing trigger 34 hasoccurred, wherein the peak 434 has acted against the proximal verticalsurface of the bottom recess 444 and the curved ramp 430 has rotatedclockwise to about the 9 o'clock position. Thereby, the anti-backuprelease lever 248 has translated proximally to exposes the anti-backuprelease button 42 from the button receptacle 422 and actuated theanti-backup mechanism 250. The relationship of the rate of clockwiserotation of the indicator gear 230 to the desired number of full firingstrokes is selected so that the curved ramp 430 continues unimpeded assubsequent firing strokes are made, as depicted in FIG. 22 wherein thetwo firing strokes have been completed moving the peak to approximatelythe twelve o'clock position. Thus, the peak 434 is proximal to andadjacent to the distal vertical edge of the upper recess 442, positionedso that a subsequent firing stroke will act upon the anti-backup releaselever 248 to cause distal horizontal movement. Note that during thesefiring strokes that the curved ramp 430 resides proximal to theindicator pin 432. Depressing the release button 42 would cause theproximal edge of the lever opening 420 to ride up onto the curved ramp430, tilting the anti-backup release lever 248 as depicted in FIG. 19.

In FIG. 23, the final firing stroke is concluding, during which the peak434 has moved to approximately 3 o'clock while moving the proximal endof the horizontal slot 440 up against the indicator pin 432, bottomingout the anti-backup release button 42, releasing the anti-backupmechanism 250 and initiating the retraction of linked transmissionfiring mechanism 150.

In FIG. 24, the unlocked anti-backup mechanism 250 has allowed thespring-powered retraction of the linked rack 200 to occur, which in turncauses a counterclockwise rotation, when viewed from the right, of theindicator gear 230. As the firing mechanism 150 begins to retract, thecounterclockwise rotation of indicator gear 230 slides the angledsurface of curved ramp 430 into ramped contact with the proximal edge ofthe top recess 442. Continued rotation of indicator gear 230 drives thecurved ramp 430 under the upper portion of backup release lever 248 andtilts or deflects lever 248 to the position shown in FIG. 19. Thetilting motion of the backup release lever 248 is provided to preventlongitudinal motion of lever 248 by the curved ramp 430 duringretraction of the linked rack 200. Should the linked rack 200 notretract at the end of the last stroke after anti-backup mechanism 250 isautomatically unlocked at the end of the firing sequence, turning theindicator knob 40 (not shown in FIGS. 20-25) would provide extra forceto retract the linked rack 200. It should further be appreciated thatduring partial firing of the firing mechanism 150, such as depicted inFIG. 22, depressing the release button 42 would also retract the linkedrack 200 by move the backup release lever 248 distally to unlock theanti-backup mechanism 250. The retraction motion continues until theindicator gear is returned to its initial position, as depicted in FIG.25.

It should be appreciated that the shape of the lever opening 420 andarcuate size of the arced ramp 430 are illustrative and may be varied toaccommodate a handle configured for a different number of firingstrokes.

It should be appreciated that the rotary release mechanism formed by theinteraction of the indicator gear 230 and the lever opening 420 may bereplaced with other linkages.

Opening Lockout.

In FIG. 26, the surgical stapling and severing instrument 10 is in itsinitial open condition with both closure and firing triggers 26, 34forward and the linked rack 200 retracted. As described above, in thisunfired condition, the indicator gear 230 presents its opening 240 incircular ridge 242 to the upper surface 244 of the locking arm 172,which is ordinarily rotated downward out of the opening 240 by theaction of the compression spring 180 between the housing structure 182and the intermediate distal side 178 of the closure release button 38.In FIG. 26, the closure release button 38 has been depressed, causingthe upper surface 244 into the opening 240. In FIG. 27, the closuretrigger 26 and the locking arm 172 are in clamping abutment afterclosing with the closure trigger 26 against the pistol grip 36 and thefiring trigger 34 swung into position for firing. The closure releasebutton 38 is not depressed, as noted by the expanded closure spring 180.The upper surface 244 of the locking arm 172 is swung below circularridge 242 and indicator gear 230 is unlocked and free to rotatecounterclockwise. The downward movement of locking arm 172 unlocks theindicator gear 230 and connected linked transmission firing mechanism150 and allows the firing trigger 34 to be actuated. Thus, as theindicator gear 230 continues to rotate with further firing, the closurerelease button 38 is precluded from releasing the clamped closuretrigger 26.

Position Indicator and Release Mechanism.

In FIG. 28, a surgical stapling and severing instrument 610 has theindicator retraction knob replaced by an alternate indicator device 640upwardly extended to present a top-accessible retraction lever 642 thatfunctions as a stuck firing retractor that may be readily actuated byeither hand. The instrument is shown opened and unfired, as indicated bythe distally forward closure and firing triggers 26, 34 and the open endeffector 12. When firing has not commenced, the retraction lever 642 isnormally distally rotated adjacent to the handle housing 154. Theindicator 640 may be coupled (not shown) to the previously describedidler gear 220 and a firing mechanism 150 as described previously inwhich the retraction lever 642 would rotate proximally as the linkedtransmission is fired, presenting a visual indication of firing as wellas allowing a way of assisting automatic retraction by applying a manualdistal force thereto as a rotary position indicator, the direction ofrotation must be reversed so it must be attached to the idler gear 220for this embodiment.

In FIG. 29, another alternate firing mechanism 650 incorporates theafore-described top-accessible retraction lever 642 and indicator device640 that is coupled to an indicator gear 660 having first and seconddwell areas 662, 664 within a toothed area 668. The first dwell area 662is presented to the idler gear 220 when the retraction lever 642 is atits distal position adjacent to the handle housing 154. Thereby, theidler gear 220 is allowed free clockwise and counterclockwise rotationas driven by the longitudinally moving linked rack 200. Should theE-beam 80 (not shown in FIG. 29) become stuck within the end effector 12for any reason and cannot be withdrawn proximally by the combinationtension/compression spring 184, the retraction lever 642 may be pulledproximally by the surgeon to rotate the indicator gear 660 clockwise, asviewed from the left. This rotational movement of the retraction lever660 rotates the indicator gear 660 and brings a curved tooth segment 670that is between the first and second dwell 662, 664 into contact withthe teeth of the idler gear 220 to operably couple the retraction lever642 to the firing mechanism 650.

Once coupled, the surgeon may apply extra force to the retraction lever642 to retract the firing mechanism 650, thereby rotating the idler gear220 counterclockwise and longitudinally moving the linked rack 200proximally to retract the E-beam 80. As the retraction lever 642 isfurther rotated to the position of FIG. 30, the idler gear 220disengages with the curved tooth segment 670 and is decoupled from theretraction lever 642 by second dwell area 664. At this point, theapplication of force has freed the stuck firing mechanism 650 and thecombination tension/compression springs 184 will fully retract thelinked rack 200.

An alternate design (not shown) involves the addition of a one way slipclutch such as a Sprague clutch or an equivalent (not shown) between theretraction lever 642 and the indicator gear 660. In the previous design,the range of motion of the retraction lever 642 is limited by contactwith the handle housing 154 at each end of the range or motion less thana full revolution. This limits the distance that the firing system 650can be retracted for one movement of the retraction lever 642. Theaddition of the one way slip clutch between the retraction lever 642 andindicator gear 660 allows the retraction lever 642 to operably engagewith the indicator gear 660 as the retraction lever 642 rotates back(distal to proximal) and disengages as the lever moves forward (proximalto distal). This ensures full retraction of the firing mechanism 650 byallowing multiple pulls on the retraction lever 642. Second dwell area664 may be removed from the indicator gear 660 to ensure more tooth totooth engagement. Additionally, the incorporation of a clutch mechanismallows the retraction lever to be rotated adjacent to the handle afteruse.

In use, the surgeon positions the end effector 12 and shaft 18 throughthe cannula or a trocar to a surgical site, positioned the anvil 14 andelongate channel 16 as opposing jaws to grasp tissue to be stapled andsevered. Once satisfied with the position of end effector 12, theclosure trigger 26 is full depressed toward the pistol grip 36 of thehandle 20, causing the upper portion 160 of the closure trigger 26 tolock against a locking arm 172 that is pivotally attached to the closurerelease button 38. Then, the firing trigger 34 is depressed and releaseda predetermined number of times to effect full firing travel to drive afiring rod 32 down the shaft 18 to the E-beam 80 in the end effector 12.During firing, the anti-backup mechanism 250 is in a locked condition,with an anti-backup plate 266 allowed to tip back, binding any proximalmotion of the firing rod 32. The distal firing motion is imparted to thefiring rod 32 by a linked transmission firing mechanism 150 thatincludes linked rack 200 proximally attached to the firing rod 32, witheach link 196 a-d pinned to adjacent links 196 a-d such that bending isallowed down into the pistol grip 36 but not upward, forming a rigidstructure when straight with a force imparted above the pivot pins 310between links 196 a-d. Specifically, a traction biasing mechanism 210coupled to the firing trigger 34 includes a biasing wheel 278 that isfrictionally coupled the handle housing 154 such that a distal firingmotion imparts an engaging bias to the pawl 270, urging the pawl 270into engagement with the linked rack 200. At the end of the stroke, thepawl 270 is lifted from firing engagement with link 196 by being broughtinto contact with angled surface 284 of the closure yoke 162. A returnmotion of the firing mechanism 150 causes the biasing wheel 278 toimpart a reversing bias to the pawl 270, holding pawl 270 above thelinked rack 200 that is thereby held in place by the anti-backupmechanism 250. Upon full firing travel, the indicator gear 230 includesthe curved ramp 430 that trips the anti-backup release lever 248 thatforces the anti-backup plate 266 into an unlocked condition, allowingthe linked rack 200, and thus the firing rod 32, to be withdrawn by acompressive force stored in a combination tension/compression spring184. Thereby, the linked rack 200 is withdrawn into the handle grip 36.Alternatively, during the firing strokes, the surgeon may depress theanti-backup release button 42 that causes the anti-backup release leverto tip. The indicator knob 40 may advantageously allow the surgeon toknow how far firing has progressed and to assist in retracting theE-beam 80 that has encountered binding.

While the present invention has been illustrated by description ofseveral embodiments and while the illustrative embodiments have beendescribed in considerable detail, it is not the intention of theapplicant to restrict or in any way limit the scope of the appendedclaims to such detail. Additional advantages and modifications mayreadily appear to those skilled in the art.

For instance, while a surgical stapling and severing instrument 10 isdescribed herein that advantageously has separate and distinct closingand firing actuation, providing clinical flexibility. However, it shouldbe appreciated that applications consistent with the present inventionmay include a handle that converts a single user actuation into a firingmotion that closes and fires the instrument.

In addition, while a manually actuated handle is illustrated, amotorized or otherwise powered handle may benefit from incorporating alinked rack as described herein, allowing reduction of the size of thehandle or other benefits. For instance, while partially stowing thelinked rack into the pistol grip is convenient, it should be appreciatedthat the pivot connection between links allows for stowing the linkparallel to the straight portion defined by the shaft and the barrel ofthe handle.

As another example, a plurality of links in a firing mechanismadvantageously allow modifications and flexible design to accommodatechanges in the firing travel needed by a device. For instance, even if arack assembly is not retracted into a grip or bent back to traversedistally, a given number of links may be used for the amount of travelrequired.

1. A surgical instrument, comprising: an end effector responsive to alongitudinal firing motion to perform a surgical operation; a shaftdistally connected to the end effector; a firing member slidinglyreceiving by the shaft to transfer the firing motion to the endeffector; and a handle proximally connected to the shaft and firingmember, comprising: a barrel portion longitudinally aligned with theshaft, a grip portion projecting from the barrel portion, a linked rackformed from a plurality of links positioned in the barrel portion anddistally coupled to the firing member, and a firing mechanism coupled tothe linked rack to impart the firing motion.
 2. The surgical instrumentof claim 1, wherein said linked rack formed from a plurality of links ispositioned in said barrel portion and in the grip portion of saidhandle.
 3. The surgical instrument of claim 1, wherein each of theplurality of links are pivotally connected.
 4. The surgical instrumentof claim 3, wherein each of the plurality of links are pivotallyconnected to an adjacent link by a connection offset from a longitudinalaxis of the linked rack.
 5. The surgical instrument of claim 2, whereineach of the plurality of links are pivotally connected to an adjacentlink by a pin member.
 6. The surgical instrument of claim 1, whereineach of the plurality of links contacts an adjacent link to form aflexible connection.
 7. The surgical instrument of claim 1, wherein eachof the plurality of links contacts an adjacent link to form a pivotableconnection that is operably configured to pivot between a straightconfiguration defined by the barrel portion and a bent configurationdefined by the grip portion.
 9. The surgical instrument of claim 1,wherein at least one link member includes a pusher surface operablyengageable with said firing mechanism for imparting firing motion tosaid firing member.
 10. The surgical instrument of claim 1, wherein saidlinked rack formed from a plurality of links is operably coupled to aretraction member to move said firing member proximally in said barrelportion.
 11. The surgical instrument of claim 10, wherein said linkedrack formed from a plurality of links is operably coupled to aretraction member that is bendable.
 12. The surgical instrument of claim11, wherein said retraction member comprises a spring.
 13. The surgicalinstrument of claim 10, wherein a distal end of said linked rack formedfrom a plurality of links is operably coupled to said retraction member.14. The surgical instrument of claim 1, wherein at least a portion ofsaid linked rack is moveable within said shaft.
 15. The surgicalinstrument of claim 1, wherein said end effector comprises a staplingdevice responsive to the longitudinal firing motion to perform thesurgical operation of stapling.
 16. The surgical instrument of claim 15,wherein said end effector comprises: an elongate channel connected tosaid shaft; an anvil pivotally coupled to said elongate channel forclamping tissue; and a staple cartridge received in said elongatechannel; wherein said firing member distally terminates in a firing baroperably configured to actuate said staple cartridge to form staples inthe clamped tissue.
 17. The surgical instrument of claim 15, furthercomprising a closure means of said stapling device.
 18. The surgicalinstrument of claim 1, further comprising a nested tension/compressionspring coupled between the firing member and the grip portion.
 19. Thesurgical instrument of claim 18, further comprising a curved bandconnected at one end proximately to a distal link of the plurality oflinks and connected at the other end to a free end of the nestedtension/compression spring.
 20. A surgical instrument, comprising: anend effector responsive to a longitudinal firing motion to perform asurgical operation; a firing actuator responsive to a user to operablyconfigured to produce the firing motion; a plurality of linked memberscoupled to the end effector to transfer the longitudinal firing motion;and a firing mechanism coupled to the firing trigger and selectivelyengageable to the linked members to transfer the firing motion from thefiring trigger through the plurality of linked members as a distallymoving longitudinal motion; wherein the each of the plurality of linkedmembers includes a pivotal connection between adjacent linked membersoperably configured to allow a bending between adjacent links in an arc;wherein the pivotal connection is positioned offset from a longitudinalaxis of the plurality of linked members when straight adjacent linkedmembers including abutting surfaces registered to arrest movementtending to bend adjacent links in an arc opposite to the offset of thepivotal connection.
 21. (canceled)
 22. The surgical instrument of claim21 claim 20, wherein the pivotal connection comprises a clevis. 23.(canceled)
 24. A surgical instrument, comprising: an implement portionresponsive to a firing motion and diametrically dimensioned forendo-surgical use, the implement portion comprising: a shaft; anelongate channel coupled to the shaft, an anvil pivotally coupled to theelongate channel, responsive to the closing motion from the shaft, andincluding an anvil channel, a firing bar including a distally presentedcutting edge longitudinally received between the elongate channel andthe anvil, and a staple device received in the elongate channel andresponsively coupled to the firing bar to form staples against theanvil; and a handle, comprising: a firing mechanism responsive to a useractuation to produce a firing motion, and a rack means responsive to thefiring mechanism to rigidly drive the firing bar and to subsequentlybendably retract.